Detailed information for February to June 2007 (Cycle 1)

Status:

Active

Frequency:

2 times per year

Record number:

4440

The primary objective of the survey is to track changes in smoking status, especially for populations most at risk, such as the 15 to 24 year olds. The survey allows Health Canada to estimate smoking prevalence by province-sex-age groups on a semi-annual basis.

Description

The Canadian Tobacco Use Monitoring Survey (CTUMS) has been conducted for Health Canada since 1999, and provides data on tobacco use and related issues. The primary objective of the survey is to track changes in smoking status, especially for populations most at risk, such as the 15 to 24 year olds. The survey allows Health Canada to estimate smoking prevalence by province-sex-age groups on a semi-annual basis.

The Cycle 1 (February to June) data of each year are released separately. The Cycle 2 (July to December) data are released within the annual summary.

Reference period: Cycle 1: February to June, Cycle 2: July to December, Annual Summary: February to December

Target population

Because the survey was conducted using a sample of telephone numbers, households (and thus persons living in households) that do not have telephone land lines were excluded from the sample population. This means that people without telephones and people with cell phones only, were excluded. People without land lines account for less than 6% of the target population. However, the survey estimates have been weighted to include persons without land lines.

Instrument design

The questionnaire design for this survey borrows heavily from the 1994 Survey on Smoking in Canada. Some questions have been added for consistency with international surveys which use the concept of smoking behaviour "in the last 30 days". In most cases questions added to CTUMS come from other Statistics Canada surveys. Interviewers are consulted about changes to the instrument.

Sampling

This is a sample survey with a cross-sectional design.

The sample design is a special two-phase stratified random sample of telephone numbers. The two-phase design is used in order to increase the representation in the sample of individuals belonging to the 15 to 19 and 20 to 24 age groups. In the first phase, households are selected using Random Digit Dialing. In the second phase, one or two individuals (or none) are selected based upon household composition.

The CTUMS, Cycle 1 conducted from February to June 2007, collected data from 9,547 respondents.

Data sources

Data collection for this reference period: 2007-02-01 to 2007-06-30

Responding to this survey is voluntary.

Data are collected directly from survey respondents.

Data were collected using computer-assisted telephone interviewing (CATI). A front-end module contains a set of standard response codes for dealing with all possible call outcomes, as well as the associated scripts to be read by the interviewers. A standard approach set up for introducing the agency, the name and purpose of the survey, the survey sponsors, how the survey results will be used, and the duration of the interview was used.

The CATI application ensured that only valid question responses were entered and that all the correct flows were followed. Edits were built into the application to check the consistency of responses, identify and correct outliers, and to control who gets asked specific questions. This meant that the data were already quite "clean" at the end of the collection process.

Error detection

The first type of error treated was errors in questionnaire flow, where questions which did not apply to the respondent (and should therefore not have been answered) were found to contain answers. In this case a computer edit automatically eliminated superfluous data by following the flow of the questionnaire implied by answers to previous, and in some cases, subsequent questions.

The second type of error treated involved a lack of information in questions which should have been answered. For this type of error a non-response or "not-stated" code was assigned to the item.

Imputation

This methodology type does not apply to this statistical program.

Estimation

The main output of the CTUMS is two microdata files, one for the household level information and one for the person level information.

For the microdata file, statistical weights were placed on each record to represent the number of sampled persons that the record represents. One weight was calculated for each household and a separate weight was calculated and provided on a different file, for each person.

The weighting for the CTUMS consists of several steps: calculation of a basic weight, followed by several adjustments such as non-response, non resolved telephone numbers and an adjustment for households with multiple telephone lines. Additional adjustments were made to account for the number of persons (0, 1 or 2) selected in the household and the over-sampling of the 15 to 24 age group. The last step of weighting consists of an adjustment to the person weights in order to make population estimates consistent with external population counts for persons 15 years and older (calibration). The following external control totals were used:

1) Monthly population totals for each province, and

2) For Cycle 1 and Cycle 2:population totals by province, sex and the following age groups: 15 to 19, 20 to 24, 25 to 34, 35 to 44, 45 to 54, 55 to 64, and 65 and over. These totals were averaged over the survey period.

For the Annual Summary:population totals by province, sex and the following age groups: 15 to 19, 20 to 24, 25 to 29, 30 to 34, 35 to 39, 40 to 44, 45 to 49, 50 to 54, 55 to 59, 60 to 64, 65 to 69, and 70 and over. These totals were averaged over the survey period.

The method called generalized regression (GREG) estimation was used to modify the weights to ensure that the survey estimates agreed with the external totals simultaneously along the two dimensions.

In order to supply coefficients of variation (CV) which would be applicable to a wide variety of categorical estimates produced from this microdata file and which could be readily accessed by the user, a set of Approximate Sampling Variability Tables has been produced. These CV tables allow the user to obtain an approximate coefficient of variation based on the size of the estimate calculated from the survey data.

The coefficients of variation in these tables are derived using the variance formula for simple random sampling and incorporating a factor which reflects the multi stage, clustered nature of the sample design. This factor, known as the design effect, was determined by first calculating design effects for a wide range of characteristics and then choosing from among these a conservative value to be used in the CV tables which would then apply to the entire set of characteristics.

The variance estimation method used until 2004 was jackknife. Starting with Cycle 1 2004, it is mean bootstrap.

Quality evaluation

Considerable time and effort was made to reduce non sampling errors in the survey. Quality assurance measures were implemented at each step of the data collection and processing cycle to monitor the quality of the data. These measures include extensive training of interviewers with respect to the survey procedures and computer-assisted telephone interviewing (CATI) application, observation of interviewers to detect problems of questionnaire design or misunderstanding of instructions and testing of the CATI application to ensure that range checks, edits and question flow were all programmed correctly.

Disclosure control

Statistics Canada is prohibited by law from releasing any information it collects which could identify any person, business, or organization, unless consent has been given by the respondent or as permitted by the Statistics Act. Various confidentiality rules are applied to all data that are released or published to prevent the publication or disclosure of any information deemed confidential. If necessary, data are suppressed to prevent direct or residual disclosure of identifiable data.

It should be noted that the "Public Use" microdata files differ in a number of important respects from the survey "master" files held by Statistics Canada. These differences are the result of actions taken to protect the anonymity of individual survey respondents. Confidentiality is ensured by suppressing and collapsing variables that may be used to identify individuals.

Revisions and seasonal adjustment

This methodology type does not apply to this statistical program.

Data accuracy

While considerable effort is made to ensure high standards throughout all stages of collection and processing, the resulting estimates are inevitably subject to a certain degree of error. These errors can be broken down into two major types: non-sampling and sampling.

Non-response is an important source of non-sampling error.

The household response rate for the CTUMS, Cycle 1, conducted from February to June 2007 was 75.2%. The person response rate was 86.6%.

The basis for measuring the potential size of sampling errors is the standard error of the estimates derived from survey results. Because of the large variety of estimates that can be produced from a survey, the standard error of an estimate is usually expressed relative to the estimate to which it pertains. This resulting measure, known as the coefficient of variation (CV) of an estimate, is obtained by dividing the standard error of the estimate by the estimate itself and is expressed as a percentage of the estimate.

Please refer to the User Guide for detailed information.

Documentation

Canadian Tobacco Use Monitoring Survey, Cycle 1, February to June 2007 - Microdata User Guide